The Blacksmith's Son by Rebecca Thomas
Captain Quentin Drake returns home after his Naval commission ends to find a young groom being beaten in the village stables. Weary from his travels, Quentin only wants a good night's sleep, but refuses to turn a blind eye to the lad's mistreatment. He intervenes, taking the lad to his room, only to discover a woman masquerading as a boy.
After Ally Lockwood's family dies, she supports herself by assisting the local blacksmith with his horses. She's not allowed to do the work as a woman, so she dresses as a boy, but her ruse is up when, due to injury, she's disrobed by a handsome stranger. What starts as a shared supper, leads to so much more...